Manufacture of uranium tetrachloride



Nov. 6, 1951 M. D. KAMEN MANUFACTURE OF URANIUM TETRACHLORIDE Filed Nov.30, 1944 INVENTOR. (ll/4X77 0. m/m /v Patented Nov. 6, 1951 MANUFACTUREOF URANIUM 'TETRACHLORIDE Martin D. .Kamen, .Berkeley, Calif., assignorto V H g the United :Statesof America as represented by the UnitedStates Atomic Energy Commission Application November 30, 1944, Serial N0. 566,009

. S-Claims.

4 This invention -re1atesl'to the manufactureof uranium tetrachlorideand more particularly to a. process using trichloroacetylchloride and anoxide of uranium for the manufacture of uranitetrachloride.

It is an object of this invention to provide an improved process ofproducing uranium tetrachloride or high chemical purity and incrystalline form. I

Another object of the invention is to provide animprovedtrichloroacetylchloride and uranium oxideprocess of producing uraniumtetrachloride inwh-ich the product is of uniform purity and*si-dereactions productive of other uranium chloridesand otherobjectionable compounds are minimized.

Another object of the invention is to provide 'an improved process ofproducing uranium tetra- V chloride which involves a reaction oftrichloroacetylchloride vapor with an oxide of uranium.

A general advance in the art and other objects which will appearhereinafter are also contemplated.

It has now been found that uranium tetrachloride can be prepared in highyield and high purity by maintaining a continuous flow oftriel-iloroacetylchloride over a charge of uranium oxide (U02, U03, orU308) heated to a temperature'within therange of 135 to 225 0. and as"near 180 C. as practicable, the pressure being substantiallyatmospheric. It has also been {found that an apparatus particularlysuited to parryout this procedure comprises vaporizing and reactionchambers so connected and arranged that the trichloroacetylchloridevapors may be forced by gravity from the vaporizing chamber into thereaction chamber and the gaseous products formed in the reaction chamberare forced to exit through the vaporizing chamber.

How the foregoing objects and related ends are accomplished will beapparent from the following xposition; in which are disclosed theprinciples, the organization, and divers embodiments of the inventionincluding the best mode contemplated iorcarrying out the same, all ofwhich is amplified by the accompanying drawing in which suitableapparatus is shown diagrammatically. Proportions of reagents arespecified as parts by weight throughout the written description.

Referring now to the single sheet of the drawing, there is shown areaction vessel 3 connected 5110 .a condenser L. which is in turnconnected to asupplyreservoir 2. An inner gas l-ine'C extends throughthe condenser and into the reaction vesgel. The reaction vessel isshaped somewhat like an hourglass and comprises a reaction chamber A anda vaporizing chamber B. These chambers are supported on sand bathheaters 5 and v6, respectively. The sand heater 5 is supported on abracket 1 and the sand heater 6 is supported on a bracket 8. Bothbrackets are secured to the upright of a stand 9 which rests on thesurface ll. At the other end of the apparatus the upright of a stand [2s pports a bracket 13 which in turn supports bracket M which in itsturn, through a clamp l5, supports the ,elevated end of the condenser atwhich end is vent .4. The upright of the stand I2 alsosupports a bracket7 Hi to which is secured a clamp H which in turn supports the reservoir2. Usually the reservoir 2 is graduated and has a gravity feed valve H3whereby the rate at which the liquid reactant trichloroacetylchloride isbeing utilized can be regulated. A container for an inert .gas underpressure (not shown) is connected at the upper end of the line C. Theouter jacket E of the condenser has the usual inlet I9 and outlet 2| fora cooling fluid.

In operation the reaction chamber A is charged with uranium dioxide andthe reaction vessel 3 connected to the condenser L. A gentle stream ofinert gas such as nitrogen is flowed into the reaction chamber A throughthe line C to sweep out the air. The flow of inert gas continuesthroughout the reaction during which time it serves to sweep outby-product gases and. excess trichloroacetylchloride vapor. Heat is thenapplied to the reaction chamber A to raise .the temperature of theuranium oxide to 180 C. and said temperature is maintained while a flowof trichloroacetylchloride is started through the valve 18. Thistrichloroacetylchloride collects in the vaporizing vessel B. After apool of the desired size has collected, heat is applied and the additionof trichloroacetylchloride from the reservoir 2 regulated to keep theliquid level in vessel B substantially constant. Upon the application ofheat to the vaporizing chamber B some of the trichloroacetylchloridevapor that is evolved enters the condenser L and is refluxed. Anotherportion of the vapor flows by gravity into the reaction chamber where itreacts with the uranium dioxide, usually forming carbon monoxide, carbondioxide, phosgene and chlorine. These gases are swept up into thecondenser along with some trichloroacetylchloride vapor by means of thenitrogen entering through the line 0. Some of the phosgene is dissolvedin the trichloroacetylchloride and carried back into the reactionchamber where it reacts with the wa :dioxide, or in vacuum.

iii'u'm dioxide. The gases which are iiot condensed in the condenser arevented through the line 4, preferably into a suitable scrubber which maybe of conventional design and operation.

During the process additional trichloroacetyh chloride is supplied as itis consumed in the reaction witli'tliecharge of uranium oxide and theprocess iscontinued until all the charge of the uranium oxide has beenconverted to U014. At this time, i. e. when the reaction of the chargeof uranium oxide is complete, the evolution-of reaction gases ceases,thereby providing a, readyf;

indication of the completion of the process.

In carrying out the present p oce s involving" uranium dioxide in thepreduc'ti'on of ranium tetrachloride the reaction temperature should bemaintained as near 180 C. as practicahhowever;

of this invention may be made without departing from the principle,breadth and spirit thereof and it is to be understood therefore thatthis invention is not limited to the specific embodiments thereof exceptas encompassed in the claims.

What is claimed is:

1; A proce'ss Qf producingurahium' tetrachloride comprisingpassingtrichloroacetylchloride vapors over an oxide of uraniummaintained at a temperature within the range of 135 C. to 225 C., and.,1ecoyering the uranium tetrachloride.

"' 2. ;Tlie process of producing uranium tetraclno- V ride comprisingreacting uranium trioxide with tricli'loroacetylchloride vapor at areaction temfper"ature wit the range of 135 C. to 225 C. in which thetrichloroacetylchloride vapor is passed continuously over. the reactionmass, and recovsatisfactory results may be obtained in the range v of135 to 225 C.

Substantially atmospheric pressure in the reaction zone is preferred,although elevated'or reduced pressures-are not objectionable and" smallpressure variations do not materially affect 'the yields or purity ofthe product. 1

' The reaction is usually complete in less than five hours, the timedepending to some extent on the crystalline form and particle size ofthe raw material, the temperature of the reaction," and the size of thecharge. A reaction time of from two to five hours'has been foundsuitable. Trichloroacetylchloride of ordinary commercial purity issatisfactory for thereaction'. The process "maybe carriedout in glass ormetal apparatus.

inert gases other than nitrogen may b i d butin the case of materialslike illuminating gas some pyrolysis may occur.

-;The present invention is particularly useful in the treatment ofuranium trioxide since itprovides a method for obtaining uraniumtetrachloride instead ofthe pentachloride normally obtained. w

After the uranium tetrachloride hasbeen produced it may be removed fromthe reaction chamber in any desired manner, such as'byremoving thereaction chamber from theremainder of the apparatus and pouring thecrystalline product therefrom. It should be" transferred to a drycontainer and maintained in storage under environment of a dry inert gassuch as'carbon It may be noted that the uranium tetrachloride mayfrequently be associated with appreciable Quantities of uraniumpentachloride formed during the course of the main'reaction; Ihese twochlorides may,vif desired, be separated ingan'y suitable manner, such asby extraction with a selective 'solvent for one of them. Carbontetrachloride is an example of a suitable solvent for this purpose,since it has a preferential solvent action towards the pentachloride.Any non-volatile im purities such as uranium oxychloride or unrev acteduranium oxide still remaining in admixture with the uraniumtetrachloride maybe separated, if desired, by a step of sublimationwherein the desired tetrachloride is sublimed away from the associatednon-volatile impurities.

The uranium tetrachloride produced 'in accordance with the presentinvention hasa crystal size and structure especialy suitable forsublimation or vaporization'in vacuum apparatus. Its form allows it tobe readily outgassed and there is little tendency for it'to betransported as a dust while being processed in region of reducedpressure.

Many' apparently widely different embodiments 152, pages 87-89.

544 and545,1917.' I

ering the uranium tetrachloride.

3.-Th'e"process comprising reacting trichloroacetylchloride vapor withuranium dioxide at a temperature of about=180 C. to produce uraniumtetrachloride,: and recovering, the uranium tetra- Ch10ride.t=:=' r r;4. The process of producing uranium tetrachloride containing someuranium pentachloride from an oxide of uranium comprising P reactingsaid oxide with the vapors of;trichloroacetylchloride at an elevatedtemperature of the orderof 180.- C. for a period of time in the range oftwo to five hours, andrecovering-r the uranium tetrachloride.

.and recovering said uranium tetrachloride.

8. The processcomprising, reacting trichloroacetyl chloride vapor withan oxide of uranium selectedjfrom the group consisting of UO2,'-U O3 andU308 at a reaction temperature of about.180

C. and in the presenceof an inert gas while at atmospheric pressure toproduce uranium tetrachloride of :high quality-and having a crystal andform suitable for processing in'an evacuated system.

W l VM'A'RTIN D. REFERENCES CITE-D,

The following references are of recordin the file. of this patent:- 1-

-A General Method of Preparing Anhydrous Chloridesed. Chauvenet'Compt.rend'., volume (Chemical Abstracts, volume 5, pa e 1036.) 1

Roscoe, Journal of the Chemical Society,'New

Sen, volume 12, pages 933-935 (1874).

'Camboulives, Comptes Renders, volume 150,

pages 175-177 (1910). Crudes, Chemical} Abstracts, volume 11 pagesMellor, Comprehensive Treatise on Inorganic and Theoretical Chemistry,volume 12; pages v and a1 (1932). Published by Longmanaor and CompanyLondoni e j f if

1. A PROCESS OF PRODUCING URANIUM TETRACHLORIDE COMPRISING PASSINGTRICHLOROACETHYLCHLORIDE VAPORS OVER AN OXIDE OF URANIUM MAINTAINED AT